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It revealed that cultivating corn in the Andes reduced dependence on quinoa and boosted calorie intake, the Guardian reports.

Corn was introduced to South America about 5,000 years ago but did not reach the Andes until humans enriched the soil with help from llama herds. The Incas would have gathered up the dung and used it to fertilise their fields.

The Incas also used llama manure as fuel to cook and make ceramics.

In July the world will celebrate the "discovery" of Macchu Picchu, the most famous Inca city.